Games and Puzzles

Find the Difference

(adapted from nrichmaths.org)

Materials:

  • paper, pencil

Draw an arrangement of empty circles like the ones below.
Place the numbers 1 to 6 in the circles so that each number is the difference between the two numbers just below it.

A pyramid made up of six equally sized circles, with three at the base and one at the top.

For example, you could have a 3 with the numbers 2 and 5 below it because the difference between 2 and 5 is 3.

Three circles. Each has a number inside: 2, 3, 5.

Extension:

When you have tried this and got more than one answer you could try other things like having four rows of circles and use the numbers 1 to 10.

5 − 2 = 3

Two Stones

(adapted from nrichmaths.org)

In China this game is known as Pong hau k’i and in Korea it is called Ou-moul-ko-no.

An X inside a square box, but the box is missing the top portion.

A game for two players.

Materials:

  • A copy of the game board above.
  • Each player needs two distinctive pieces (e.g., pebbles, coins, game pieces, paper circles)

To play:
Place the two pieces at the top and two at the bottom as shown below.

Same image as above, but red dots are added to the top two corners, and blue dots at the bottom two corners.

Take turns to slide one pebble along a line to an empty spot. (There are 5 spots to move to, the 4 corners and middle).
The first move will be to the middle.

To win: block your opponent so that they cannot move.

Next time you play swap start positions on the board with your opponent.

The Collection Box

(adapted from nrichmaths.org)

A photograph of a child holding colourful stones in their hands.
Materials:

  • 6 stones
  • 3 X 3 grid that is big enough to place the stones in

Find 6 interesting stones. You could use some that you already collected or you could go for a stone hunt the next time you go for a walk.

We are going to place the 6 stones in a box which has 9 little square compartments.

A 3 by 3 blank grid.Can you place six stones into the box so that there are just two stones in every column and every row? Can you find more than one way? How many ways can you find?